Fan system and motor control circuit

ABSTRACT

A control circuit is electrically connected to at least one fan device. The fan device has a motor and generates a sensing signal. The control circuit receives a power-source signal and the sensing signal and includes a power converting unit, a control unit and a switch unit. The power converting unit receives the power-source signal and thus respectively outputs a first power-source signal and a second power-source signal according to the power-source signal. The control unit receives the first power-source signal and the sensing signal and thus generates a control signal according to the sensing signal. The switch unit receives the control signal and generates at least one switch signal according to the control signal. The fan device receives the second power-source signal and the switch signal and drives the motor according to the switch signal.

CROSS REFERENCE TO RELATED APPLICATIONS

This Non-provisional application claims priority under 35 U.S.C. §119(a)on Patent Application No(s). 096117762 filed in Taiwan, Republic ofChina on May 18, 2007, the entire contents of which are herebyincorporated by reference.

BACKGROUND OF THE INVENTION

1. Field of Invention

The present invention relates to a system and a control circuit thereof,and in particular to a fan system and a motor control circuit thereof.

2. Related Art

With the high development of technology, the demands on functions of anelectronic apparatus are increased, and the number and the integrationdensity of the used electrical elements are also increased. Thus, theheat dissipation becomes more important. In other words, the heatdissipating efficiency directly influences the reliability and thelifetime of the electronic apparatus.

A fan is usually provided to serve as a heat-dissipating device. Thenumber of fans can be increased or decreased at the end of the customersystem according to different requirements of the clients, and a controldevice or a control chip is provided to drive and control the rotatingspeed of the fan in the fan system. Therefore, the rotating speed of thefan can be adjusted according to the actual operating condition of thecustomer system.

Referring to FIG. 1, a conventional fan system 1 uses a control circuit11 and a plurality of fan devices 12 electrically connected together.The power switch unit 113 of the control circuit 11 receives an externalpower V to generate a supply source signal SS outputted to the powerprocessing unit 111. The power processing unit 111 of the controlcircuit 11 generates a first power-source signal S01, a secondpower-source signal S02 and a third power-source signal S03 according tothe supply source signal SS. The first power-source signal S01 serves asa supplied power for the first control unit 112 of the control circuit11, and the first control unit 112 generates a first control signal SC1accordingly.

In addition, the second power-source signal S02 and the thirdpower-source signal S03 of the power processing unit 111 arerespectively a positive power and a negative power. The first controlunit 112 has a microprocessor or a micro-control chip, and the firstcontrol signal SC1 generated thereby is a rotating speed control signal.

Each of the fan devices 12 has a motor 121, a winding 122, a sensingunit 123, a power unit 124, a second control unit 125 and a switch unit126 electrically connected together. The power unit 124 respectivelyreceives and provides the second power-source signal S02 and the thirdpower-source signal S03 to the sensing unit 123 and the second controlunit 125. The second control unit 125 receives the first control signalSC1 and generates a second control signal SC2 to be outputted to theswitch unit 126 according to the first control signal SC1, and enablesthe switch unit 126 to switch the current direction of the winding 122to drive the motor 121 to rotate. In addition, among these fan devices12, the second control unit 125 includes a microprocessor or amicro-control chip, and the second control signal SC2 generated therebyis a rotating speed control signal.

At this time, the sensing unit 123 senses the rotating speed of themotor 121 to generate a sensing signal SE to be outputted to the firstcontrol unit 112 of the control circuit 11 so that the first controlunit 112 again generates the first control signal SC1 to be outputted tothe second control units 125 of the fan devices 12 according to thesensing signal SE, and the rotating speeds of the motors 121 can becontrolled.

Because the fan devices 12 of the fan system 1 have many membersdisposed therein, and the second control units 125 and the power units124 of the fan devices 12 are respectively for controlling and supplyingthe powers to the fan devices 12. The control circuit 11, which may alsorespectively control the operations of the fan devices 12 through thefirst control unit 112, and the power processing unit 111 provide therequired powers to the first control circuit 112 and the fan devices 12.That is, the fan system 1 can not only control the fan devices 12through the control circuit 11, but also control the rotating speeds ofthe fan devices 12 through the fan devices 12 themselves. Thus, theoverall cost is wasted because the control circuit 11 and the fandevices 12 have the members with the same or similar features andeffects. In addition, when one of the fan devices 12 is damaged, it isinconvenient and time-consuming to replace the damaged fan device 12because the fan device 12 has too many members disposed therein tooccupy a large space.

SUMMARY OF THE INVENTION

In view of the foregoing, the present invention is to provide a fansystem and a motor control circuit thereof, wherein the overall cost canbe reduced and various members can be integrated together.

To achieve the above, the present invention discloses a motor controlcircuit, which is connected to a fan device. The fan device includes amotor and generates a sensing signal. The motor control circuit receivesa power-source signal and the sensing signal, and includes a powerconverting unit, a control unit and a switch unit. The power convertingunit receives a power-source signal and respectively outputs a firstpower-source signal and a second power-source signal according to thepower-source signal. The control unit receives the first power-sourcesignal and the sensing signal, and generating a control signal accordingto the sensing signal. The switch unit receives the control signal andgenerates at least one switch signal according to the control signal.The fan device receives the second power-source signal and the switchsignal and drives the motor according to the switch signal.

To achieve the above, the present invention also discloses a fan systemincluding a control circuit and at least one fan device. The controlcircuit receives a power-source signal, and includes a power convertingunit, a control unit and a switch unit. The power converting unitreceives the power-source signal and respectively outputs a firstpower-source signal and a second power-source signal according to thepower-source signal. The control unit receives the first power-sourcesignal and generates a control signal. The switch unit receives thecontrol signal and generates at least one switch signal according to thecontrol signal. The fan device is electrically connected to the controlcircuit and receives the second power-source signal and the switchsignal. The fan device has a motor, a winding and a sensing memberelectrically connected together. The winding receives the switch signaland drives the motor according to the switch signal. The sensing memberreceives the second power-source signal and senses a rotating speed ofthe motor to generate a sensing signal to be transmitted to the controlunit.

In summary, the motor control circuit of the present invention has thepower converting unit, the control unit and the switch unit electricallyconnected together, and each fan device electrically connected to thecontrol circuit has the winding, the sensing member and the motorelectrically connected together. Compared with the prior art, the numberof the switch units in the control circuit of the present invention isincreased, and only the winding, the motor and the sensing member areprovided in the fan device. That is, unlike the prior art, each fandevice has the switch unit, the control unit, the power switch unit andthe power processing unit. The fan device and the control circuit of thepresent invention can share the power converting unit and the controlunit of the control circuit so that the internal circuits of the fandevices can be simplified and the cost can be reduced. In addition, theoriginal control unit and the switch unit, which tend to be damaged ortend to cause the malfunction, are disposed in the control circuit sothat the fan device can be directly packaged to achieve the waterprooffunction. Furthermore, the manufacturing cost of one single fan devicecan be greatly decreased. Thus, when any fan device is damaged, it canbe directly replaced in a time-saving manner. In addition, the damagedfan devices may be replaced one by one. Furthermore, because the numberof members of the fan device is decreased, the size of the fan devicecan be reduced to facilitate the assembling process so that thewaterproof effect can be obtained and the overall reliability can beenhanced.

BRIEF DESCRIPTION OF THE DRAWINGS

The present invention will become more fully understood from thedetailed description and accompanying drawings, which are given forillustration only, and thus are not limitative of the present invention,and wherein:

FIG. 1 is a schematic illustration showing a conventional fan system;

FIG. 2 is a schematic illustration showing a fan system according to apreferred embodiment of the present invention; and

FIG. 3 is a schematic illustration showing another fan system accordingto the preferred embodiment of the present invention, wherein a fandevice has a control circuit and nine fan devices.

DETAILED DESCRIPTION OF THE INVENTION

The present invention will be apparent from the following detaileddescription, which proceeds with reference to the accompanying drawings,wherein the same references relate to the same elements.

Referring to FIG. 2 a fan system 2 according to the preferred embodimentof the present invention includes a control circuit 21 and one fandevice 22 or a plurality of fan devices 22. In this embodiment, thecontrol circuit 21 is electrically connected to the fan devices 22 andreceives an external power-source signal SV and a sensing signal SEcoming from the fan device 22. The fan system 2 can be implemented by aplurality of fan devices 22. Of course, it is also possible to use onlyone fan device 22. In this example, the fan system 2 has a plurality offan devices 22.

The control circuit 21 of this embodiment has a power converting unit211, a control unit 212 and at least one switch unit 213.

The power converting unit 211 has a power switch 21A and a powerprocessor 21B. The power switch 21A receives the power-source signal SVand is implemented as having a filter element, a rectifier element, atransformer or a voltage converting element so that the power-sourcesignal SV is transformed into the supply source signal SP by theabove-mentioned element. In this embodiment, the power-source signal SVis implemented as a digital power or an analog power, and the voltageconverting element can be a digital-to-analog converter or ananalog-to-digital converter.

The power processor 21B is electrically connected to the power switch21A, receives the supply source signal SP, and respectively outputs afirst power-source signal S11 and a second power-source signal S12according to the supply source signal SP. The first power-source signalS11 of this embodiment is for supplying the power for each unit of thecontrol circuit 21, and the second power-source signal S12 is providedto the fan devices 22.

In addition, the second power-source signal S12 has a firstsub-power-source signal S1A and a second sub-power-source signal S1B. Inthis example, the first sub-power-source signal S1A is a positivepower-source signal, and the second sub-power-source signal S1B is anegative power-source signal. Of course, the positive power-sourcesignal and the negative power-source signal can also be exchanged.

The control unit 212 receives the first power-source signal S11 and thesensing signal SE of the fan device 22 and the control unit 212 includesa microprocessor or a micro-control chip, which converts the sensingsignal SE into a control signal SC. The control unit 212 of thisembodiment is implemented as a digital control circuit, the controlsignal SC can be a pulse width modulation (PWM signal, and the sensingsignal SE can be a fan rotating speed value.

The switch unit 213 receives the control signal SC and generates a firstswitch signal SW1 and a second switch signal SW2 according to thecontrol signal SC. The switch unit 213 of this embodiment includes aplurality of switch elements, which can constitute a half-bridge circuitor a full-bridge circuit. For example, two switch elements constitutethe half-bridge circuit, or four switch elements constitute thefull-bridge circuit. The switch elements may be ametal-oxide-semiconductor field-effect transistor (MOSFET) or a bipolarjunction transistor (BJT). In addition, the number of the half-bridgecircuits or the full-bridge circuits corresponds to the number of thefan devices 22.

Each fan device 22 receives the second power-source signal S12, thefirst switch signal SW1 and the second switch signal SW2, and has amotor 221, a winding 222 and a sensing member 223 electrically connectedtogether. In this embodiment, the motor 221 of each fan device 22 can bea DC brushless motor.

The winding 222 receives the first switch signal SW1 and the secondswitch signal SW2 and drives the motor 221 according to the first switchsignal SW1 and the second switch signal SW2. The sensing member 223receives the first sub-power-source signal S1A and the secondsub-power-source signal SIB of the second power-source signal S12,senses the rotating speed of the motor 221, and generates the sensingsignal SE according to the rotating speed of the motor 221. In thisembodiment, the sensing member 223 is a Hall integrated circuit.

In order to make the content of the present invention clearer, a fansystem 3 and its operations will be illustrated according to an example.Herein, the fan system 3 includes a control circuit 31 and nine fandevices 32.

As shown in FIG. 3, the control circuit 31 is electrically connected tothe fan devices 32 in this embodiment. The control circuit 31 has apower converting limit 311, a control unit 312 and a switch unit 313.Each fan device 32 has a motor 321, a winding 322 and a sensing member323.

The control circuit 31 receives the power-source signal SV inputted fromthe outside, and thus transforms the power-source signal SV into thesupply source signal SP through the power switch 31A. A power processor31B receives the supply source signal SP and thus respectively outputs afirst power-source signal S11 and a second power-source signal S12according to the supply source signal SP. The first power-source signalS11 provides the powers for the control unit 312 and the switch units313 of the control circuit 31, and the second power-source signal S12provides the powers for the sensing members 323 of the fan devices 32.

The control unit 312 generates a control signal SC to be outputted tothe switch units 313 to enable the switch units 313 to respectivelygenerate a first switch signal SW1 and a second switch signal SW2, whichare to be respectively transmitted to the windings 322 of the fandevices 32, according to the control signal SC.

At this time, the winding 322 of each fan device 32 starts and drivesthe motor 321 according to the first switch signal SW1 and the secondswitch signal SW2. Meanwhile, the sensing member 323 of each fan device32 starts to sense the rotating speed of the motor 321, generates asensing signal SE according to the rotating speed of the motor 321, andtransmits the sensing signal SE to the control unit 312 of the controlcircuit 31.

The control unit 312 obtains the condition of the rotating speed of themotor 321 according to the sensing signal SE of each fan device 32,generates the control signal SC to be outputted to the switch units 313according to different requirements, and then enables the winding 322 todrive the motor 321 and to adjust the rotating speed of the motoraccording to the first switch signals SW1 and the second switch signalsSW2 of the switch limits 313.

It is to be noted that the switch units 313 and the fan devices 32transmit the first switch signals SW1 and the second switch signals SW2through only two signal lines in the embodiment of FIG. 3. In practice,however, it is also possible to increase the number of the signal linesaccording to the number of the switch units 313 and the number of thefan devices 32 so that the switch units 313 can respectively adjust therotating speeds of the corresponding fan devices 32.

In summary, the control circuit of the present invention has the powerconverting unit, the control unit and the switch unit electricallyconnected together, and each fan device electrically connected to thecontrol circuit has the winding, the sensing member and the motorelectrically connected together. Compared with the prior art, the switchunits in the control circuit of the present invention is provided, andonly the winding, the motor and the sensing member are provided in thefan device. That is, unlike the prior art, in which each fan device hasthe switch unit, the control unit, the power switch unit and the powerprocessing unit, the fan device and the control circuit of the presentinvention can share the power converting unit and the control unit ofthe control circuit so that the internal members of the fan devices canbe simplified and the cost can be reduced. In addition, the originalcontrol unit and the switch unit, which tend to be damaged or tend tocause the malfunction, are disposed in the control circuit so that thefan device can be directly packaged to achieve the waterproof function.Furthermore, the manufacturing cost of one single fan device can begreatly decreased.

Although the present invention has been described with reference tospecific embodiments, this description is not meant to be construed in alimiting sense. Various modifications of the disclosed embodiments, aswell as alternative embodiments, will be apparent to persons skilled inthe art. It is, therefore, contemplated that the appended claims willcover all modifications that fall within the true scope of the presentinvention.

What is claimed is:
 1. A control circuit electrically connected to a fandevice having a plurality of removable fan motor assemblies eachcomprising a motor, a winding and a sensing member, the control circuitcomprising: a power converting unit for receiving a power-source signaland respectively outputting a first power-source signal and a secondpower-source signal according to the power-source signal; a control unitfor receiving the first power-source signal and generating a controlsignal, where the control signal is a pulse width modulation (PWM)signal; and a switch unit for receiving the first power-source signal,the control signal and generating a first switch signal and a secondswitch signal according to the control signal, wherein the fan devicereceives the second power-source signal, the first switch signal and thesecond switch signal and drives the motors of the removable fan motorassemblies according to the first switch signal and the second switchsignal.
 2. The control circuit according to claim 1, wherein the controlunit generates the control signal according to a sensing signal or a fanrotating speed value of the fan device.
 3. The control circuit accordingto claim 1, wherein the power converting unit comprises: a power switchfor receiving the power-source signal and generating a supply sourcesignal according to the power-source signal; and a power processor forreceiving the supply source signal and respectively outputting the firstpower-source signal and the second power-source signal according to thesupply source signal.
 4. The control circuit according to claim 3,wherein the power switch has a filter element, a rectifier element, atransformer or a voltage converting element, and the supply sourcesignal is generated according to the power-source signal through thefilter element, the rectifier element, the transformer or the voltageconverting element.
 5. The control circuit according to claim 1, whereinthe second power-source signal has a first sub-power-source signal and asecond sub-power-source signal and the first sub-power-source signal andthe second sub-power-source signal are respectively a positivepower-source signal and a negative power-source signal.
 6. The controlcircuit according to claim 1, wherein the control unit comprises amicroprocessor, a micro-control chip or a digital control unit.
 7. Thecontrol circuit according to claim 1, wherein the switch unit is ahalf-bridge circuit or a full-bridge circuit.
 8. The control circuitaccording to claim 1, wherein the switch unit transmits the first switchsignal and the second switch signal to the fan device through two signallines to adjust a rotating speed of the fan device.
 9. A fan system,comprising: a control circuit for receiving a power-source signal,wherein the control circuit comprises a power converting unit, a controlunit and a switch unit, the power converting unit receives thepower-source signal and respectively outputs a first power-source signaland a second power-source signal according to the power-source signal,the control unit receives the first power-source signal and generates acontrol signal, where the control signal is a pulse width modulation(PWM) signal and the switch unit receives the first power-source signal,the control signal and generates a first switch signal and a secondswitch signal according to the control signal; and a fan devicecomprising a plurality of removable fan motor assemblies including amotor, a winding, and a sensing member, electrically connected to thecontrol circuit and each fan motor assembly receives the secondpower-source signal, the first switch signal and the second switchsignal, wherein the fan device and the control circuit share the powerconverting unit and the control unit of the control circuit, where eachwinding receives the first switch signal and the second switch signaland drives the motor according to the first switch signal and the secondswitch signal, the sensing member receives the second power-sourcesignal and senses a rotating speed of the motor to generate a sensingsignal to be transmitted to the control unit.
 10. The fan systemaccording to claim 9, wherein the power converting unit comprises: apower switch for receiving the power-source signal and generating asupply source signal according to the power-source signal; and a powerprocessor for receiving the supply source signal and respectivelyoutputting the first power-source signal and the second power-sourcesignal according to the supply source signal.
 11. The fan systemaccording to claim 10, wherein the power switch has a filter element, arectifier element, a transformer and a voltage converting elementelectrically connected to each other, and the supply source signal isgenerated according to the power-source signal through the filterelement, the rectifier element, the transformer and the voltageconverting element.
 12. The fan system according to claim 9, wherein thesecond power-source signal has a first sub-power-source signal and asecond sub-power-source signal, and the first sub-power-source signaland the second sub-power-source signal are respectively a positivepower-source signal and a negative power-source signal.
 13. The fansystem according to claim 9, wherein the control unit comprises amicroprocessor, a micro-control chip or a digital control unit.
 14. Thefan system according to claim 9, wherein the sensing signal is a fanrotating speed value.
 15. The fan system according to claim 9, whereinthe switch circuit is a half-bridge circuit or a full-bridge circuit.16. The fan system according to claim 9, wherein the sensing member is aHall integrated circuit.
 17. The fan system according to claim 9,wherein the switch unit transmits the first switch signal and the secondswitch signal to the winding of the fan device through two signal lines.